Rejection of multiple tone interference in DS spread-spectrum systems employing minimum redundant transversal filters

A direct-sequence spread-spectrum (DSSS) receiver using a new transversal filter structure called the minimum redundant transversal filter (MRTF), for combating narrow-band interference is proposed. The tap spacings of the MRTF are selected by a particular non-uniform thinning technique so as to achieve better cancellation resolution than the conventional transversal filter structure, but with a lesser number of tap weights and at a far reduced level of complexity. Analytical expressions for the signal-to-noise ratio improvement factors are derived under the conditions of multiple tone interference. The effectiveness of the new suppression filter is examined and the results obtained for the system reveals the fact that the MRTF structure leads to superior performance especially when the frequencies of the jamming tones are near the carrier frequency of the modulated signal